Applications of convective heat transfer devices range from chemical refineries to air conditioning to locomotion to computing to machining. In this disclosure we look to minimize the power required for forced fluid convection heat transfer devices to operate. This improvement is important for portable devices, for applications attempting to minimize power consumption, for minimizing noise generation, and for minimizing wear.
In particular we look to reduce the thermal resistance for heat sinks applied to electronic devices such as insulated gate bipolar transistors (IGBTs), silicon controlled rectifiers, microprocessors, injection laser diodes, and thermoelectric modules.
In U.S. Pat. No. 5,507,092 Akachi describes a spiral of flat fins stamped from a sheet and attached to a rigid base. Each fin is attached at one end only. In U.S. Pat. No. 5,358,032 Arai describes a folded wire mesh brazed to a rigid base. Wires in the mesh parallel to the base block fluid flow without significant contribution to heat transfer. In U.S. Pat. No. 3,416,218 Armenoff describes making an expanded metal cellular core. The bonding techniques are applicable to a fin array heat sink. In U.S. Pat. No. 5,158,136 Azar a pin field heat sink that generates recirculating flow. The pins are attached at one end, and air is sheared many times as it passes through the pin field. In U.S. Pat. No. 5,304,846 Azar describes heat sinks composed of dense fin arrays. The fins are formed as slots in a solid plate. In U.S. Pat. No. 5,150,748 Blackmon describes a heat radiator composed of a shag rug of conductive fibers. The spacings between the fibers are not uniform. In U.S. Pat. No. 5,299,080 Brady describes a heat sink pin array in the form of a shaving cream brush. The air flow across each pin is greatest at the greatest distance from the heated surface. In U.S. Pat. No. 4,449,164 Carlson describes a plenum that ducts air over a radial fin array. The flows in adjacent channels are parallel. In U.S. Pat. No. 4,843,693 Chisholm describes a folded wire mesh brazed to a rigid base. Wires in the mesh parallel to the base block fluid flow without significant contribution to heat transfer. In U.S. Pat. No. 5,121,613 Cox describes an A-frame Freon cooler. Heat is supplied to the fin arrays from embedded pipes. In U.S. Pat. No. 4,993,482 Dolbear uses wire coils compressed between parallel plates as compliant thermal shunt between the two plates. Heat is not being transferred to a fluid. In U.S. Pat. No. 5,590,712 Fisher describes a method of manufacturing a pin fin array. Each fin is attached at one end only. In U.S. Pat. No. 4,753,290 Gabuzda describes a radial fin array attached to a rigid base. The spacing between the fins is not uniform, and the fins are attached at one end only. In U.S. Pat. No. 231,485 Gold described wire coils trapped between radiator plates for heating air. Individual loops of the coils are circular, and they are not attached to their neighboring loops. In U.S. Pat. No. 4,768,581 Gotwald describes multiple dense fin arrays fed by multiple ducts. The fins are laminated together at one end only. In U.S. Pat. No. 5,388,635 Gruber describes fin arrays formed in a metal cooling sheet fed by multiple ducts. The fins are formed as slots partially through the metal sheet. In U.S. Pat. No. 5,058,665 Harada describes a stacked plate heat exchanger in which each plate has an array of circular holes. In U.S. Pat. No. 5,195,576 Hatada describes a heat sink composed of corrugated fine wires individually attached to a heated plate. The wires are attached only at the heated plate. In U.S. Pat. No. 4,777,560 Herrell stacks right and left handed stamped elements to make a fin array. The air flow across the fins is the greatest at the greatest distance from the heated surface. In U.S. Pat. No. 1,516,430 Hess attaches continuous wire loops to a pipe in a heat exchanger. Each loop is attached only at one point. In U.S. Pat. No. 4,879,891 Hinshaw describes a method of forming a dense fin array out of a solid. The fins are attached at their bases only. In U.S. Pat. No. 4,884,331 Hinshaw describes a method of forming a pin fin array out of a solid. The pin fins are attached at their bases only. In U.S. Pat. No. 3,327,779 Jacoby describes a pin grid heat sink formed by pressing staples through a flexible sheet. The resulting pins are attached at their bases only. In U.S. Pat. No. 5,353,867 Jaspers describes a pin fin array formed from stacked sheets in which the pattern of holes in the sheets forms the pins and the parallel supply and exhaust channels. The design is constrained to have substantially less than 50% of the heated surface area spanned by the combined pin cross sectional area. In U.S. Pat. 5,486,980 Jordan describes a pin fin array cooled by air initially impinging along the axis of each pin. The pins are attached at their bases only. In U.S. Pat. No. 3,372,741 Kaiser uses elongated wire loops to make a pin array that bridges radially between two concentric pipes. The gaps between the loops are not uniform. In U.S. Pat. No. 5,241,452 Kitajo describes a fin array in which the ends of the fins are tapered to enhance air flow near the heated surface. The fins are attached at their bases only. In U.S. Pat. No. 5,005,640 Lapinski describes a heat transfer manifold containing many parallel flow channels. The flow in adjacent channels is parallel. In U.S. Pat. No. 5,311,928 Marton describes louvered fin arrays formed from stamped metal. The design is constrained to have substantially less than 50% of the heated surface area spanned by the combined fin cross sectional area. In U.S. Pat. No. 4,898,234 McGovern describes a porous block heat exchanger with an interdigitated manifold. The flows in adjacent channels in the manifold are parallel. In U.S. Pat. Pat. No. 5,381,859 Minakami describes a pin fin heat sink assembled as a transformer core with spacers between slotted plates. The minimum number of slotted plates in a stack is three. In U.S. Pat. No. 4,821,389 Nelson teaches a method to make a pin fin array by radially slicing a spool of wire with a soluble coating. The resulting arrays of parallel wires are end bonded to two support plates. In U.S. Pat. No. 4,884,630 Nelson describes a liquid manifold for a heat sink containing multiple parallel channels. The flows in adjacent channels are parallel. In U.S. Pat. No. 5,180,001 Okada describes layering metal mesh to form a heat sink. The fluid flow passage cross sections are non-uniform. In U.S. Pat. No. 3,706,127 Oktay describes a pin fin array in the shape of a shaving cream brush formed by electroless plated iron filings. The air flow across each pin is greatest at the greatest distance from the heated surface. In U.S. Pat. No. 1,559,180 Prat described wire coils trapped between radiator plates for heating air. Individual loops of the coils are circular, and they are not attached to their neighboring loops. In U.S. Pat. No. 2,544,183 Rogers describes a heat exchanger utilizing wire coils of elongated loops in a circumferential arrangement between two plates. The spacing between the loops is not constant. In U.S. Pat. No. 5,561,338 Roberts describes an arc lamp heat sink in which a copper strip is corrugated to form radial fins between concentric cylinders. The spacing between the fins is not uniform. In U.S. Pat. No. 4,421,161 Romania describes a wire helix formed to transfer heat from an electronic package to air. The resulting wire loops are elongated parallel to the surface of the package, and the loops are not attached at their ends distant from the package. In U.S. Pat. No. 4,884,631 Rippel describes a fin array composed of bonded and expanded sheet metal. Metal sheets nearly parallel to the base block fluid flow without significant contribution to heat transfer. In U.S. Pat. No. 1,716,743 Still describes elongated wire coil fins arranged in a spiral about a hot pipe. The gaps between the wires are non-uniform. In U.S. Pat. No. 2,093,256 Still describes a heat exchanger in which flattened wire helixes are wound in elongated loops around support wires or tubes. The loops are specified as having an open pitch. In U.S. Pat. No. 4,450,472 Tuckerman describes a heat transfer technique in which slots cut in the back of a semiconductor chip to form fins. The fins are attached at their bases only. In U.S. Pat. No. 5,212,625 van Andel describes a pin fin field in which each pin is bent to collectively form interdigitated flow channels. The flow resistance through the pins is non-uniform, and the flows in adjacent channels are parallel. In U.S. Pat. No. 5,205,353 Willemsen describes a heat exchanger utilizing porous metal and interdigitated flow channels. The flows in adjacent channels are parallel. In U.S. Pat. No. 4,009,752 Wilson described a fin array formed by clamping individual fins in upper and lower capture plates. The resulting soldered assembly is rigid and non-compliant. The above identified U.S. patents are hereby incorporated by reference.